The governor of the Mexican state of Guerrero resigned Thursday, nearly one month after the unresolved disappearance of 43 students that is linked to politicians, police and drugs cartels.

Ángel Aguirre Rivero said on social media that he was confident he had "made the responsible decision" in stepping down. He added that a regional parliament would choose his replacement.

The students from a rural teachers training college went missing after a confrontation with police in the town of Iguala on September 26. The circumstances that led to the violence remain unclear. However, six people were killed at the scene and dozens were wounded after police and armed civilians opened fire on three buses filled with students.

Authorities have ordered the arrest of Iguala's mayor, his wife and an aide, alleging the trio were the masterminds behind the attack. Dozens of local police and members of the Guerreros Unidos drug gang have been detained in connection with the case.

There has been no word on the missing men. Initial DNA testing shows the charred bodies found in several mass graves in Iguala are not the students.

Ongoing protests around Mexico demand answers from the government, which is under international criticism for human rights abuses committed by security forces.